It had been more than 40 years since Foster City’s Peninsula Sinai Congregation in California faced an antisemitic graffiti attack.

That streak ended over the weekend when a nearly 2-foot-wide swastika was discovered spray-painted on the south side of the synagogue.

A congregant out for a late afternoon stroll on Sunday, noticed the vandalism and contacted the synagogue.

“We’re fairly confident it was placed in the early morning hours of Saturday, sometime after midnight,” said Matthew Parks, president of the 66-year old Conservative congregation. “It’s a little disturbing because that meant for the entire day … people were walking by, with a park across the street. And not until Sunday was it noticed and reported.”

The graffiti, which was painted over the next day, included both a swastika and other symbols of unclear meaning. Parks requested that the image of the symbols be blurred out in photos to avoid amplifying any hidden message.

“For right now, we are following the recommendation of law enforcement and other security professionals to withhold that part of the graffiti,” Parks said.

Parks said congregants were notified immediately of the incident, as were other local Jewish institutions, including congregations, day schools and JCCs. Foster City police have increased patrols in the area, he said.

“There was quite a bit of shock and consternation,” Park said of the reaction among congregants. “We came together for Tuesday night minyan and had a much larger crowd than usual.”

He appreciated the “outpouring of support” from rabbis and board members of other area synagogues, as well as messages of sympathy from other faith-based institutions. Parks was especially grateful for a vandalism kit the congregation received from the Peninsula JCC in Foster City.

“It’s basically a box containing paint, rollers, a tarp and instructions on how to handle incidents of vandalism,” Parks said. “I’m having our security committee and grounds committee add that to our inventory.”